There were those at that time who, wise beyond their generation, recognized the full meaning of the advent of steam, and saw that it must supplant sails altogether as the motive power for ships. These advocated that new constructions should be given full steam-power, with sails as an auxiliary. But the old pride in the sailing-ship, with her taunt and graceful spars, could not be made to yield at once to the innovation; nor could the old traditions pointing to the necessity of full sail-power be dispelled; so it was considered a sufficient concession to admit steam on any terms, and thus the conservative and temporizing course was adopted of retaining full sail-power, and utilizing steam as an auxiliary. The United States government was not alone in this policy. It was the course pursued by all other maritime nations, and for some years the United States retained the lead in producing the most perfect types in this new phase of naval construction. In 1854 Congress passed an act authorizing the construction of the _Merrimac_ class of frigates. The famous ships immediately built under this act were the _Merrimac_, _Wabash_, _Minnesota_, _Roanoke_, and _Colorado_. All of these vessels got to sea during 1856 and 1857, and were followed, at an interval of ten years, by the _Franklin_, which was a larger ship, and an improvement on the original type. The _Franklin_ was built at Kittery, Maine. Her length is 266 feet, beam 54 feet, draught of water 24 feet. She has a displacement of 5170 tons, and attains a speed of 10 knots per hour with an indicated horse-power of 2065. The capacity of her coal-bunkers is 860 tons. Her frames are of seasoned live-oak, and she is in use as a receiving-ship. [Illustration: U. S. FRIGATE “FRANKLIN,” OF THE “MERRIMAC” CLASS.] The _Merrimac_ was the first vessel of this type which got to sea. She was sent to European waters, and on her arrival in England, early in 1856, she became at once the object of the closest scrutiny, resulting in the unqualified approval of foreign naval architects. The English Admiralty proceeded to imitate the type, and many keels were soon laid in order to reproduce it. The ships built after this model were the crack ships of the time in the English navy, and carried the flags of the commanders-in-chief of fleets. In 1858, 1859, and 1860, the _Hartford_ class of large corvettes appeared. These are full-rigged ships. The class comprises the _Hartford_, _Brooklyn_, _Pensacola_, _Richmond_, and _Lancaster_. [Illustration: U. S. SLOOP-OF-WAR “HARTFORD.”]